A power conversion apparatus used in an uninterruptible power supply apparatus generally includes a converter that converts AC power from a commercial AC power supply into DC power and an inverter that converts the DC power into AC power with a desired frequency and a desired voltage.
For example, WO 2010/095241 (PTL 1) discloses an uninterruptible power supply apparatus formed of a power conversion apparatus including a three-level converter and a three-level inverter. In this power conversion apparatus, the three-level converter and the three-level inverter each include a plurality of semiconductor switching devices.
In the power conversion apparatus described above, if any of the plurality of semiconductor switching devices shorts out through breakage, overcurrent or overvoltage may occur. In PTL 1, a fuse is connected between one terminal of each semiconductor switching device and a DC bus (DC positive bus, DC negative bus, or DC neutral bus). This configuration melts the fuse to interrupt a path through which current flows if any of the semiconductor switching devices shorts out, thus preventing an occurrence of overcurrent or overvoltage.